Ask the doc. I can't see why it would have been wrong - but it seems like it you were not refluxing for that particular time.
Maybe you have specific reflux triggers, not just a valve that is always open.
Have you tried keeping a food journal/log with times, what you eat or drink and symptoms an hour and two hours after eating? I was able to control my reflux by learning my triggers and avoiding them. (Mine turned out to be sulfite.) I eventually did need surgery, but that was due to an accident causing my stomach to be pushed into my chest and the valve being permanently open.
It's also possible that you have "silent GERD." This is when you have symptoms that are not ordinary reflux, but it is still kept under control with acid reducers (PPIs).